I have found these sites to be invaluable when researching information on SKS rifles. PerfectUnion BBS is not affiliated with any of the remote sites and while they are believed to be extremely accurate the information on them is the responsibility of the site owners.

This site http://www.surplusrifle.com/index.asp is going down for good in March of 2007. If there are any downloads there that you need such as maintenance videos or PDF files would be a good time to get them.

Stainless Steel valve uses torque bolt to lock in place in stead of a button, it's also slightly over sized if you need one that just a little bigger for gas tubes that are worn. Look on the bottom of the page.